Life365_v2 2 1_Users_Manual

•

UPE

Wanessa Lima

29/07/2020

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Life-365™ Service Life Prediction Model™

and Computer Program for Predicting the Service Life and
Life-Cycle Cost of Reinforced Concrete
Exposed to Chlorides

Version 2.2.1
January 15, 2014

Produced by the Life-365™ Consortium III

Life-365TM v1.0 and v2.2 Credits
The Life-365™ v1.0 program and manual were written by E. C. Bentz and M. D. A.
Thomas under contract to the Life-365 Consortium I, which consisted of W. R. Grace
Construction Products, Master Builders, and the Silica Fume Association. The Life-365™
v2.2 program and manual are adaptations of these documents, and were written by M. A.
Ehlen under contract to the Life-365 Consortium III, which consists of BASF Admixture
Systems, Cortec, Epoxy Interest Group (Concrete Reinforcing Steel Institute), Euclid
Chemical, Grace Construction Products, National Ready-mixed Concrete Association,
Sika Corporation, Silica Fume Association, Slag Cement Association
“Life-365 Service Life Prediction Model” and “Life-365” are trademarks of the Silica
Fume Association. These trademarks are used with permission in this manual and in the
computer program.

Table of Contents
1
Introduction 7
2
Life-365™ Service Life Prediction Model™ 9
2.1
Predicting the Initiation Period 9
2.2
Predicting the Propagation Period 23
2.3
Repair Schedule 24
2.4
Probabilistic Predictions of Initiation Period 24
2.5
Estimating Life-Cycle Cost 24
2.6
Calculating Life-Cycle Cost 25
3
Life-365™ Computer Program Users Manual 26
3.1
Installing Life-365 26
3.2
Starting Life-365 28
3.3
Project Tab 30
3.4
Exposure Tab 31
3.5
Concrete Mixtures Tab 33
3.6
Individual Costs Tab 37
3.7
Life-Cycle Cost Tab 38
3.8
Service Life and Life-Cycle Cost Reports Tabs 42
3.9
Supporting Features 44
3.10
Advanced Analysis: Service Life Uncertainty 45
3.11
Special Applications: Epoxy-Coated Rebar, Top Reinforcing Only 51
4
Module for Estimating Maximum Surface Concentration 53
4.1
ASTM C1556 Method 53
4.2
How Life-365 Uses the ASTM C1556 Method 55
4.3
Software Algorithm 61
4.4
ASTM C1556 References 63
5
Life-365™ Background Information 65
5.1
Service-Life Estimate 65
5.2
Input Parameters for Calculating the Service Life (Time to First Repair) 67
5.3
Input Parameters for Calculating Life-cycle cost 77
5.4
Summary 77
References 78
Appendix A. Test Protocols for Input Parameters 81

List of Figures
Figure 2.1. Examples of Concrete Surface History and Environmental Temperatures .... 11
Figure 2.2. Relationship Between D28 and w/cm .............................................................. 12
Figure 2.3. Effect of Silica Fume on DSF .......................................................................... 13
Figure 2.4. Effects of Fly Ash and Slag on Dt .................................................................. 14
Figure 2.5. Effects of Membranes and Sealers ................................................................. 16
Figure 2.6. Limited Modeling of Diffusion in Slabs Deeper than 10 Inches .................... 17
Figure 2.7. Single Quadrant in 2D Column ...................................................................... 19
Figure 2.8. Single Quadrant Variables in 2D Column ...................................................... 20
Figure 2.9. Life-365™/ERF Comparison: Over Depth at Time of Initiation ................... 23
Figure 3.1. Windows Java Settings Panel ......................................................................... 27
Figure 3.2. Determining Current Java Version in Mac OS X Terminal Console ............. 28
Figure 3.3. Startup Screen ................................................................................................. 29
Figure 3.4. Project Tab ...................................................................................................... 30
Figure 3.5. Exposure Tab .................................................................................................. 32
Figure 3.6. Concrete Mixtures Tab ................................................................................... 33
Figure 3.7. Service Life Tab ............................................................................................. 35
Figure 3.8. Cross-section Tab ........................................................................................... 35
Figure 3.9. Concrete Initiation Graphs ............................................................................. 36
Figure 3.10. Concrete Characteristics Tab ........................................................................ 36
Figure 3.11. Individual Costs Tab ..................................................................................... 37
Figure 3.12. Default Concrete and Repair Costs .............................................................. 38
Figure 3.13. Life-Cycle Cost Tab ..................................................................................... 39
Figure 3.14. Life-Cycle Cost: Timelines Tab ................................................................... 40
Figure 3.15. Life-Cycle Cost: Sensitivity Analysis Tab ................................................... 41
Figure 3.16. Service Life (SL) Report Tab ....................................................................... 42
Figure 3.17. LCC Report Tab ........................................................................................... 43
Figure 3.18. Pop-up Menu for Copying a Graph to Clipboard ......................................... 44
Figure 3.19. Default Settings and Parameters Tab ........................................................... 44
Figure 3.20. Online Help .................................................................................................. 45
Figure 3.21. Concrete Mixtures Tab: Initiation Time Uncertainty Tab ............................ 46
Figure 3.22. Service Life Uncertainty Prompt .................................................................. 47
Figure 3.23. Initiation Probability Graphs ........................................................................ 47
Figure 3.24. Initiation Period Probability, by Year .......................................................... 48
Figure 3.25. Cumulative Initiation Per. Prob., by Year .................................................... 48
Figure 3.26. Initiation Variation Graph ............................................................................ 49
Figure 3.27. Life-Cycle Costs Tab with Modify Uncertainty Panel ................................. 50
Figure 3.28. Modify Uncertainty Panel ............................................................................ 50
Figure 3.29. Default and Modified Steel Costs for Hybrid Epoxy/Black Steel Slab ........ 51
Figure 4.1. ASTM Estimate of Surface Chloride Concentration ...................................... 54
Figure 4.2. New Life-365 Exposure Tab .......................................................................... 56
Figure 4.3. ASTM New Set Data Entry Panel .................................................................. 56
Figure 4.4. ASTM C1556 Data ......................................................................................... 57
Figure 4.5. ASTM Panel with Data Entered ..................................................................... 58
Figure 4.6. ASTM Panel: ASTM Calculations Tab .......................................................... 59
5
Figure 4.7. Accessing an ASTM Dataset in a Life-365 Project ........................................ 60
Figure 4.8. Life-365 ASTM Guidance Tab ......................................................................61
Figure 4.9. Verification of Results for Levenberg-Marquardt Algorithm ........................ 62
Figure 5.1. Components of Concrete Service Life ........................................................... 65
Figure 5.2. Chloride Levels, by Region of North America .............................................. 69
Figure 5.3. Effects of w/cm on Diffusion Coefficient ...................................................... 71
Figure 5.4. Effects of Silica Fume on Diffusion Coefficient ............................................ 72
Figure 5.5. Effects of Age on Diffusivity ......................................................................... 74

List of Tables
Table 1. Effects of Slag and Fly Ash on Diffusion Coefficients ...................................... 14
Table 2. Effects of CNI on Threshold ............................................................................... 15
Table 3. Life-365 v2.2 and ERF Comparison ................................................................... 22
Table 4. Build-up Rates and Maximum Surface Concentration, Various Zones .............. 68
Table 5. Build-up Rates and Maximum %, by Structure Type ......................................... 70
Table 6. Values of m, Various Concrete Mixtures ........................................................... 73
Table 7. Doses and Thresholds, Various Inhibitors .......................................................... 76
Table 8. Model Inputs and Test Conditions ...................................................................... 87

Life-365™ Disclaimer

The Life-365™ Manual and accompanying Computer Program are intended for guidance
in planning and designing concrete structures exposed to chlorides while in service. They
are intended for use by individuals who are competent to evaluate the significance and
limitations of their content and recommendations, and who will accept responsibility for
the application of the material it contains. The members of the consortium responsible for
the development of these materials shall not be liable for any loss or damage arising there
from.
Performance data included in the Manual and Computer Program are derived from
publications in the concrete literature and from manufacturers’ product literature. Specific
products are referenced for informational purposes only.
Users are urged to thoroughly read this Manual so as to fully understand the capabilities
and limitations of the Life-365™ Service Life Prediction Model™ and the Computer
Program.
7
1 Introduction
The corrosion of embedded steel reinforcement in concrete due to the penetration of
chlorides from deicing salts, groundwater, or seawater is the most prevalent form of
premature concrete deterioration worldwide and costs billions of dollars a year in
infrastructure repair and replacement. There are currently numerous strategies available
for increasing the service life of reinforced structures exposed to chloride salts, including
the use of:
• low-permeability (high-performance) concrete,
• chemical corrosion inhibitors,
• protective coatings on steel reinforcement (e.g. epoxy-coated or galvanized steel),
• corrosion-resistant steel (e.g. stainless steel),
• non-ferrous reinforcement (e.g. fiber-reinforced plastics),
• waterproofing membranes or sealants applied to the exposed surface of the
concrete,
• cathodic protection (applied at the time of construction), and
• combinations of the above.
Each of these strategies has different technical merits and costs associated with their use.
Selecting the optimum strategy requires the means to weigh all associated costs against the
potential extension to the life of the structure. Life-cycle cost analysis (LCCA) is being
used more and more frequently for this purpose. Life-365 LCCA uses estimated initial
construction costs, protection costs, and future repair costs to compute the costs over the
design life of the structure. Many concrete protection strategies may reduce future repair
costs by reducing the extent of future repairs or by extending the time between repairs.
Thus, even though the implementation of a protection strategy may increase initial
construction costs, it may still reduce life-cycle cost by lowering future repair costs.
A number of models for predicting the service life of concrete structures exposed to
chloride environments or for estimating life-cycle cost of different corrosion protection
strategies have been developed and some of these are available on a commercial basis.
The approaches adopted by the different models vary considerably and consequently there
can be significant variances between the solutions produced by individual models. This
caused some concern among the engineering community in the 1990s and in response, in
May 1998 the Strategic Development Council (SDC) of the American Concrete Institute
(ACI) identified the need to develop a “standard model” and recommended that a
workshop be held to investigate potential solutions. In November 1998, such a workshop,
entitled “Models for Predicting Service Life and Life-Cycle Cost of Steel-Reinforced
Concrete”, was sponsored by the National Institute of Standards and Technology (NIST),
ACI, and the American Society for Testing and Materials (ASTM). A detailed report of
the workshop is available from NIST (Frohnsdorff, 1999). At this workshop a decision
was made to attempt to develop a “standard model” under the jurisdiction of the existing
ACI Committee 365 “Service Life Prediction.” Such a model would be developed and
8
maintained following the normal ACI protocol and consensus procedure for producing
committee documents.
Another mechanism that results in corrosion of steel is carbonation of the concrete cover
and the reduction of pH at the level of the reinforcing steel. Corrosion due to carbonation
is a relatively low probability and is generally associated with lower quality concrete and
reduced cover. The Life-365 Service Life Prediction Model does not cover carbonation.
In order to expedite the process, a consortium was established under ACI’s SDC to fund
the development of an initial life-cycle cost model based on the existing service life model
developed at the University of Toronto (see Boddy et al., 1999). The funding members of
this consortium, known as the Life-365 Consortium, were Master Builders Technologies,
Grace Construction Products and the Silica Fume Association. Life-365 Version 1.0 was
released in October 2000, and later revised as Version 1.1 in December 2001 to
incorporate minor changes.
The current version has many limitations in that a number of assumptions or
simplifications have been made to deal with some of the more complex phenomena or
areas where there is insufficient knowledge to permit a more rigorous analysis. Users are
encouraged to run their own user-defined scenarios in tandem with minor adjustments to
the values (e.g. D28, m, Ct, Cs, tp) selected by Life-365. This will aid in the development of
an understanding of the roles of these parameters and the sensitivity of the solution to the
values.
This manual is divided into five parts:
1. Model Description. This section provides a detailed explanation of how
the Life-365 model estimates the service life (time to cracking and first
repair) and the life-cycle cost associated with different corrosion protection
strategies. The mathematical equations and empirical relationships
incorporated in the model are presented in this section.
2. Users Manual. This section is an operator’s manual that gives instructions
on how to use Life-365, the input parameters required, and the various
options available to the user.
3. ASTM C1556 Module. This section describes how Life-365 provides and
uses the ASTM C1556 process of estimating maximum surface chloride
concentration based on calculations from field data.
4. Background Information.This section presents published and other
information to support the relationships and assumptions used in the model
to calculate service life and life-cycle cost. A discussion of the limitations
of the current model is also presented.
5. Appendix A. Test Protocols for Input Parameters. This section provides
recommended protocols for determining some of the input parameters used
in Life-365.
9
2 Life-365™ Service Life Prediction Model™
Life-365 analyses can be divided into four sequential steps:
• Predicting the time to the onset of corrosion of reinforcing steel, commonly called
the initiation period, ti;
• Predicting the time for corrosion to reach an unacceptable level, commonly called
the propagation period, tp; (Note that the time to first repair, tr, is the sum of these
two periods: i.e. tr = ti + tp)
• Determining the repair schedule after first repair; and
• Estimating life-cycle cost based on the initial concrete (and other protection) costs
and future repair costs.
2.1 Predicting the Initiation Period
The initiation period, ti, defines the time it takes for sufficient chlorides to penetrate the
concrete cover and accumulate in sufficient quantity at the depth of the embedded steel to
initiate corrosion of the steel. Specifically, it represents the time taken for the critical
threshold concentration of chlorides, Ct, to reach the depth of cover, xd. Life-365 uses a
simplified approach based on Fickian diffusion that requires only simple inputs from the
user.
2.1.1 Predicting Chloride Ingress due to Diffusion
The model predicts the initiation period assuming diffusion to be the dominant
mechanism. Given the assumption that there are no cracks in the concrete, Fick’s second
law is the governing differential equation:
, Eq. 1
where C = the chloride content,
D = the apparent diffusion coefficient,
x = the depth from the exposed surface, and
t = time.
The chloride diffusion coefficient is a function of both time and temperature, and Life-365
uses the following relationship to account for time-dependent changes in diffusion:
, Eq. 2
where D(t) = diffusion coefficient at time t,
Dref = diffusion coefficient at time tref (= 28 days in Life-365), and
m = diffusion decay index, a constant.
€
dC
dt
= D⋅
d2C
dx 2
€
D t( ) = Dref ⋅
tref
t
#
$
%
&
'
(
m
10
Life-365 selects values of Dref and m based on the details of the composition of the
concrete mixture (i.e., water-cementitious material ratio, w/cm, and the type and
proportion of cementitious materials) input by the user. In order to prevent the diffusion
coefficient from continually decreasing with time, the relationship shown in Eq. 2 is
assumed to be only valid up to 25 years, beyond which D(t) stays constant at the D(25
years) value.
Life-365 uses the following relationship to account for temperature-dependent changes in
diffusion:
, Eq. 3
where D(T) = diffusion coefficient at time t and temperature T,
Dref = diffusion coefficient at time tref and temperature Tref,
U = activation energy of the diffusion process (35000 J/mol),
R = gas constant, and
T = absolute temperature.
In the model, tref = 28 days and Tref = 293K (20°C). The temperature T of the concrete
varies with time according to the geographic location selected by the user. If the required
location cannot be found in model database, the user can input temperature data available
for the location.
The chloride exposure conditions (e.g., rate of chloride build up at the surface and
maximum chloride content) are set by the model based on one of three alternate
approaches:
1. Life-365 provides a database of values based on the type of structure (e.g., bridge
deck, parking structure), the type of exposure (e.g., to marine or deicing salts), and
the geographic location (e.g., New York, NY).
2. The user can input their own data for these parameters.
3. The user can calculate a maximum surface concentration based on measured
chloride levels using ASTM C1556 (and input their own data on time to buildup).
The solution for time to initiation of corrosion is carried out using a finite difference
implementation of Eq. 1 where the value of D is modified at every time step using Eq. 2
and Eq. 3.
2.1.2 Input Parameters for Predicting the Initiation Period
The following inputs are required to predict the initiation period:
• Geographic location;
• Type of structure and nature of exposure;
• Depth of clear concrete cover to the reinforcing steel (xd), and
€
D T( ) = Dref ⋅ exp
U
R
⋅
1
Tref
−
1
T
$
%
& &
'
(
) )
*
+
,
,
-
.
/
/
11
• Details of each protection strategy scenario, such as water-cement ratio, type and
quantity of supplementary cementitious materials and corrosion inhibitors, type of
steel and coatings, and type and properties of membranes or sealers.
From these input parameters the model selects the necessary coefficients for calculating
the time to corrosion, as detailed above.
Surface Chloride Build Up
The model determines a maximum surface chloride concentration, Cs, and the time taken
to reach that maximum, tmax, based on the type of structure, its geographic location, and
exposure, as input by the user. For example, if the user selects a bridge deck in an urban
area of Moline, Illinois, the model will use the surface concentration profile shown in the
left panel of Figure 2.1. Alternatively, the user can input his own profile, in terms of
maximum surface concentration and the time (in years) to reach that maximum. Life-365
v2.2 includes the additional ability to input a maximum surface concentration based on
ASTM C1556 data calculations.

Figure 2.1. Examples of Concrete Surface History and Environmental
Temperatures
Temperature Profile
The model determines yearly temperature profiles based on the user’s input for
geographical location using a database compiled from meteorological data. For example,
if the user selects Moline, Illinois, the model will use the temperature profile in the right
panel in Figure 2.1. Alternatively the user can input temperature profile relevant to the
location, in terms of monthly average temperatures in either degrees Celsius (if the
project is using SI units) or degrees Fahrenheit (if the project is using US units).
Base Case Concrete Mixture
The base case concrete mixture assumed by the model is plain portland cement concrete
with no special corrosion protection strategy. For the base case, the following values are
assumed:
D28 = 1 x 10(-12.06 + 2.40w/cm) meters-squared per second (m2/s) , Eq. 4
12
m = 0.20, and Eq. 5
Ct = 0.05 percent (% wt. of concrete). Eq. 6
The relationship between D28 and the water-cementitious materials ratio (w/cm) is based
on a large database of bulk diffusion tests. The nature of the relationship is shown in
Figure 2.2 (corrected to 20°C). The value of m is based on data from the University of
Toronto and other published data and decreases the diffusion coefficient over the course
of 25 years, after which point Life-365 holds it constant at the 25-year value, to reflect
the assumption that hydration is complete. The value of Ct is commonly used for service-
life prediction purposes (and is close to a value of 0.40 percent chloride based on the
mass of cementitious materials for a typical concrete mixture used in reinforced concrete
structures).

Figure 2.2. Relationship Between D28 and
w/cm
It should be noted that these relationships pertain to concrete produced with aggregates of
normal density and may not be appropriate for lightweight concrete.
Effect of Silica Fume
The addition of silica fume is known to produce significant reductions in the permeability
and diffusivity of concrete. Life-365 applies a reduction factor to the value calculated for
portland cement, DPC, based on the level of silica fume (%SF) in the concrete. The
following relationship,which is again based on bulk diffusion data, is used:
DSF = DPC ·e-0.165·SF. Eq. 7
The relationship is only valid up to replacement levels of 15-percent silica fume. The
model will not compute diffusion values (or make service life predictions) for higher
levels of silica fume.
Relationship Between D28 and W/CM
1E-12
1E-11
1E-10
0.3 0.4 0.5 0.6
W/CM
D
if
fu
s
io
n
C
o
e
ff
ic
ie
n
t,
D
2
8
(
m
2
/s
)
13

Figure 2.3. Effect of Sil ica Fume on DSF
Life-365 assumes that silica fume has no effect on either Ct or m.
Effect of Fly Ash and Slag
Neither fly ash nor slag are assumed to effect the early-age diffusion coefficient, D28, or
the chloride threshold, Ct. However, both materials impact the rate of reduction in
diffusivity and hence the value of m. The following equation is used to modify m based
on the level of fly ash (%FA) or slag (%SG) in the mixture:
m = 0.2 + 0.4(%FA/50 + %SG/70) . Eq. 8
The relationship is only valid up to replacement levels of 50 percent fly ash or 70 percent
slag and m itself cannot exceed 0.60 (which would occur if fly ash and slag were used at
these maximum levels), that is, m must satisfy m ≤ 0.60. Life-365 will not compute
diffusion values (or make service life predictions) for higher levels of these materials, and
after 25 years holds the diffusion constant at the 25-year value to reflect that hydration is
complete.
Figure 2.4 shows the effect of m for three mixtures with w/cm = 0.40 and with plain
portland cement (PC), 30 percent slag, and 40 percent fly ash. Table 1 lists these mixture
proportions and their computed the diffusion coefficients, for 28 days, 10 years, and 25
years. For years greater than 25, Life-365 uses the computed 25-year diffusion
coefficient.
Effect of Silica Fume
0
0.2
0.4
0.6
0.8
1
0 5 10 15
Silica Fume (%)
D
S
F
/
D
P
C
(
m
2
/s
)
14

Figure 2.4. Effects of Fly Ash and Slag on Dt

Table 1. Effects of Slag and Fly Ash on Diffusion Coefficients

m
(<=0.60)
D28
(x 10-13 m2/s)
D10y
(x 10-13 m2/s)
D25y
(x 10-13 m2/s)
PC 0.20 79 30 25
30 percent SG 0.37 79 13 9.3
40 percent FA 0.52 79 6.3 3.9

Effect of Corrosion Inhibitors
The model accounts for two chemical corrosion inhibitors with documented performance:
calcium nitrite inhibitor (CNI) and Rheocrete 222+ (a proprietary product from Master
Builders; in the Life-365 software, it is referred to as “A&E,” for “amines and esters”). It
is intended that other types of inhibitors can be included in the model when appropriate
documentation of their performance becomes available.
Ten dosage levels of 30 percent solution calcium nitrite are permitted in Life-365. The
inclusion of CNI is assumed to have no effect on the diffusion coefficient, D28, or the
diffusion decay coefficient, m. The effect of CNI on the chloride threshold, Ct, varies
with dose as shown in the following table.
15
Table 2. Effects of CNI on Threshold
CNI Dose Threshold, Ct
(% wt. conc.)
litres/m3 gal/cy
0 0 0.05
10 2 0.15
15 3 0.24
20 4 0.32
25 5 0.37
30 6 0.40

In addition, a single dose of Rheocrete 222+ (or amines and esters, as it is referred to in
the software) is permitted in the model; the dose is 5 litres/m3 concrete. This dose of the
admixture is assumed to modify the corrosion threshold to Ct = 0.12 percent (by mass of
concrete). Furthermore, it is also assumed that the initial diffusion coefficient is reduced to
90 percent of the value predicted for the concrete without the admixture and that the rate
of chloride build up at the surface is decreased by half (in other words it takes twice as
long for Cs to reach its maximum value). These modifications are made to take account of
the pore modifications induced by Rheocrete 222+ (or amines and esters), which tend to
reduce capillary effects (i.e. sorptivity) and diffusivity.
Effect of Membranes and Sealers
Membranes and sealers are dealt with in a simplified manner: Life-365 assumes that both
membranes and sealers only impact the rate of chloride build-up, and can only be
reapplied up to the time of the first repair. Membranes start with an efficiency of 100
percent, which deteriorates over the lifetime of the membrane; a lifetime of 20 years; and
no re-applications. This means that the rate of build-up starts at zero and increases linearly
to the same rate as that for an unprotected concrete at 20 years. As shown in the left panel
of Figure 2.5, surface chlorides for unprotected concrete (labeled “PC”) increases at a rate
of 0.04 percent per annum and reaches a maximum concentration of 0.60 percent at 15
years. In the right panel, surface chlorides for concrete protected by a default membrane
increase at a lower rate, but then reach the same rate after 20 years. The user can also set
his own values for initial efficiency, lifetime of the membrane, and re-applications.

Figure 2.5. Effects of Membranes and Sealers
Sealers are dealt with in the same way, except that the default lifetime is only 5 years. The
example in Figure 2.5 shows the effect of reapplying the sealer every 5 years. Each time
the sealer is applied, the build-up rate is reset to zero and then allowed to build up back to
the unprotected rate (0.04 percent per annum in the example) at the selected lifetime of the
sealer (5 years in the example).
Effect of Epoxy-Coated Steel
The presence of epoxy-coated steel does not affect the rate of chloride ingress in concrete,
nor would it be expected to impact the chloride threshold of the steel at areas where the
steel is unprotected. Consequently, the use of epoxy-coated steel does not influence the
initiation period, ti. However, it is assumed in the model that the rate of damage build up is
lower when epoxy-coated steel is present and these effects are dealt with by increasing the
propagation period, tp, from 6 years to 20 years.
Effect of Stainless Steel
In the current version of Life-365 it is assumed that grade 316 stainless steel has a
corrosion threshold of Ct = 0.50 percent (i.e., ten times the black steel Ct of 0.05 percent).
2.1.3 Initiation-Period Fickian Solution Procedures
The Life-365 Computer Program uses a finite-difference implementation of Fick’s second
law, the general advection-dispersion equation. Implicit in the model are the following
assumptions:
• The material under consideration is homogeneous (e.g. no surface effects);
• The surface concentration of chlorides around the concrete member is constant,
for any given point in time;
• The properties of the elements are constant during each time step, calculated at
the start of each time step; and
17
• The diffusion constant is uniform over the depth of the element.
• For concrete slabs (one-dimension calculations), the diffusion process is only
active in the top portion of the slab and therefore only modeled in Life-365 in the
top 10 inches of a slab that is deeper than that (Figure 2.6).

Figure 2.6. Limited Modeling of Diffusion in Slabs Deeper than 10 Inches
One-Dimension Calculations (Walls and Slabs)
For the one-dimensional slabs and walls, the time-to-initiation is estimated
deterministically using a one-dimensional Crank-Nicolson finite difference approach,
where the future levels of chlorides in the concrete are a function of current chloride
levels. Specifically, the level of chloride at a given slice of the concrete i and next time
period t+1 is determined by
,
where
r = dt
(dt)
2(dx)2
is dimensionless Courant–Friedrichs–Lewy (CFL) number,
dt = the diffusion coefficient at time t, in meters-squared per second,
dt = the time step, in seconds,
dx = the distance increment (total depth divided by number of slices),
= chloride level (%wt of concrete) at time t and slice i ,
i = 1,…, I is the particular slice of concrete (and i = 0 is the top slice that holds
the external concentration of chlorides), and
t = the time step in theinitiation-to-corrosion period.
Rearranging terms and putting them in matrix form, the chloride levels at each time
period t+1 are solved from the equation
,
where
€
−rui+1
t+1 + 1+ 2r( )uit+1 − rui−1t+1 = rui+1t + 1− 2r( )ruit + rui−1t
€
ui
t
€
AUt+1 = BUt
18
A = ai
t+1{ }=
1 0 0 0 0
−r 1+ 2r −r 0 0
... ... ... ... ...
0 0 −r 1+ 2r −r
0 0 0 0 1
"
#
$
$
$
$
$
$
%
&
'
'
'
'
'
'
,
,
B = bi
t+1{ }=
1 0 0 0 0
r 1− 2r r 0 0
... ... ... ... ...
0 0 r 1− 2r r
0 0 0 0 1
"
#
$
$
$
$
$
$
%
&
'
'
'
'
'
'
, and

The individual ui, j
t+1 are then be solved by rearranging terms:
.
The number r is required to be small for numerical accuracy.
Two-Dimension Calculations (Square and Round Columns)
For two-dimensional columns, the time-to-initiation ideally can be estimated using a two-
dimensional Crank-Nicolson equation:
(1+ 2r)ui, j
t+1−
r
2
ui−1, j
t+1 +ui+1, j
t+1 +ui, j−1
t+1 +ui, j+1
t+1( ) = (1− 2r)ui, jt
+
r
2
ui−1, j
t +ui+1, j
t +ui, j−1
t +ui, j+1
t( )
Eq. 9
where each term is defined as in the one-dimensional case above, but where each {i, j}
term is a square from the ith row and jth column of a square matrix of terms. Since the
chloride surface concentrations and interior steel locations are symmetric to the vertical
and horizontal centerlines of the column cross-section, we can solve using just one
€
Ut+1 = ui
t+1{ } =
u1
t+1
...
ui
t+1
...
uI
t+1
"
#
$
$
$
$
$
$
%
&
'
'
'
'
'
'
€
Ut = ui
t{ } =
u1
t
...
ui
t
...
uI
t
"
#
$
$
$
$
$
$
%
&
'
'
'
'
'
'
€
Ut+1 = A−1BUt
19
quadrant of the cross-section. As shown in Figure 2.7, we use the upper left quadrant,
where the “surface” cells are the external levels of chloride, and therefore exogenous
parameters in the calculations, and the “interior” cells are those to be calculated.
surface surface surface surface
surface interior (a) interior (a) interior (b)
surface interior (a) interior (a) interior (b)
surface interior (c) interior (c) interior (d)
!
"
#
#
#
#
$
%
&
&
&
&

Figure 2.7. Single Quadrant in 2D Column
Also due to symmetry, we can represent the interior cells (those that need to be
calculated) by using reflections of certain values; specifically, particular ui, j
t+1 values in
Eq. 9 above are represented by their mirror value.
1. Interior (a) points are solved for using Eq. 9 above.
2. Interior (b) points are solved for using the following modified version:
(1+ 2r)ui, j
t+1−
r
2
ui−1, j
t+1 +ui+1, j
t+1 +ui, j−1
t+1 +ui, j−1
t+1( ) = (1− 2r)ui, jt
+
r
2
ui−1, j
t +ui+1, j
t +ui, j−1
t +ui, j−1
t( )
Eq. 10
3. Interior (c) points are solved for using the following modified version:
(1+ 2r)ui, j
t+1−
r
2
ui−1, j
t+1 +ui−1, j
t+1 +ui, j−1
t+1 +ui, j+1
t+1( ) = (1− 2r)ui, jt
+
r
2
ui−1, j
t +ui−1, j
t +ui, j−1
t +ui, j+1
t( )
Eq. 11
4. Interior (d) points are solved for using the following modified version:
(1+ 2r)ui, j
t+1−
r
2
ui−1, j
t+1 +ui−1, j
t+1 +ui, j−1
t+1 +ui, j−1
t+1( ) = (1− 2r)ui, jt
+
r
2
ui−1, j
t +ui−1, j
t +ui, j−1
t +ui, j−1
t( )
Eq. 12
As an example, to solve the interior points at time t+1 for the 9 interior cells in Figure
2.7, we have 9 equations and 9 unknowns, where the variables are declared according to
Figure 2.8.
20
u0,0 u0,1 u0,2 u0,3
u1,0 u1,1 u1,2 u1,3
u2,0 u2,1 u2,2 u2,3
u3,0 u3,1 u3,2 u3,3
!
"
#
#
#
#
#
#
#
#
#
$
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&
&
&
&
&
&
&
&
&

Figure 2.8. Single Quadrant Variables in 2D Column
To help simplify the equations, given that at time t+1 all t values are known, the right-
hand side of each equation can be represented by a function
ui, j (t) = (1− 2r)ui, j
t +
r
2
ui−1, j
t +ui+1, j
t +ui, j−1
t +ui, j+1
t( ) ,
the nine equations are then:
(1+ 2r)u1,1
t+1−
r
2
u0,1
t+1 +u2,1
t+1 +u1,0
t+1 +u1,2
t+1( ) = u1,1(t)
(1+ 2r)u1,2
t+1−
r
2
u0,2
t+1 +u2,2
t+1 +u1,1
t+1 +u1,3
t+1( ) = u1,2 (t)
(1+ 2r)u1,3
t+1−
r
2
u0,3
t+1 +u2,3
t+1 +u1,2
t+1 +u1,2
t+1( ) = u1,3(t)
(1+ 2r)u2,1
t+1−
r
2
u1,1
t+1 +u3,1
t+1 +u2,0
t+1 +u2,2
t+1( ) = u2,1(t)
(1+ 2r)u2,2
t+1 −
r
2
u1,1
t+1 +u3,1
t+1 +u2,1
t+1 +u2,3
t+1( ) = u2,2 (t)
(1+ 2r)u2,3
t+1−
r
2
u1,1
t+1 +u3,1
t+1 +u2,2
t+1 +u2,2
t+1( ) = u2,3(t)
(1+ 2r)u3,1
t+1−
r
2
u2,1
t+1 +u2,1
t+1 +u3,0
t+1 +u3,2
t+1( ) = u3,1(t)
(1+ 2r)u3,2
t+1−
r
2
u2,2
t+1 +u2,2
t+1 +u3,1
t+1 +u3,3
t+1( ) = u3,2 (t)
(1+ 2r)u3,3
t+1−
r
2
u2,3
t+1 +u2,3
t+1 +u3,2
t+1 +u3,2
t+1( ) = u3,3(t)
Eq. 13
To be able to solve for each
€
ui, j
t+1
through matrix mathematics, the square matrices of
€
ui, j
t+1
and
€
ui, j
t
terms are converted to (i*j) × 1 matrices, e.g.,
21
Ut+1 = ui, j
t+1{ }=
u0,0
t+1 u0,1
t+1 ...
u1,0
t+1 u1,1
t+1 ...
... ... ...
ui, j
t+1
... ... ...
... uI−1,J−1
t+1 uI−1,J
t+1
... uI ,J−1
t+1 uI ,J
t+1
"
#
$
$
$
$
$
$
$
$
$
$
$
%
&
'
'
'
'
'
'
'
'
'
'
'
⇒ Ut+1 = uk
t+1{ }=
u0,0
t+1
u0,1
t+1
...
u1,0
t+1
u1,1
t+1
...
ui, j
t+1
...
uI−1,J−1
t+1
uI−1,J
t+1
...
uI ,J−1
t+1
uI ,J
t+1
"
#
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
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.
For the 9x9 example, then, the
€
˙ U t +1 vector is
€
˙ U t +1 = uk
t +1{ } =
u 0,0
u 0,1
u 0,2
u 0,3
u 1,0
u1,1
u1,2
u1,3
u 2,0
u2,1
u2,2
u2,3
u 3,0
u3,1
u3,2
u3,3
"
#
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
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&
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and the equations in Eq. 13 can be represented by
€
A ˙ U t +1. The chloride levels at each time
period t+1 are solved from the equation
€
A ˙ U t +1 = B ˙ U t ,
22
or
€
˙ U t +1 = A−1B ˙ U t . Eq. 14
Inverting matrix A, however, is computationally expensive; computing initiation periods
could take from 1 to 15 minutes (or longer) per alternative. To overcome this time
expense, Life-365 uses a successive relaxation technique (SOC).
Validation of Initiation Period Estimates
Significant work has been conducted to compare the estimates of initiation period
calculated by Life-365 v2.2 against those of other models. With regard to 1-D (slab and
wall) estimates, the Life-365 v2.2 estimates have been compared to both Fick’s second
law Error Function Solutions as well as Life-365 v1.1 estimates. With regard to 2-D
square and round columns, the Life-365 v2.2 estimates have been compared to Life-365
v1.1 estimates.
For the 1-D case in particular, work has been conducted to compare the Life-365 v2.2
estimates (and indirectly the Life-365 v1.1 estimates) of initiation period to Fick’s second
law error function solution,
c(x, t) = cs 1− erf
x
4Dt
"
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'
(
)
*
+
,
- , Eq. 15
(where c(x,t) is the concentration at depth x and time t,
€
cs is the surface concentration, erf
is the error function, and D is the diffusion coefficient), which for particular settings are
theoretically equivalent.1 Tests of estimates by the two methods show a good ‘fit’ of the
two concentration values shown in Figure 2.9.2
Table 3. Life-365 v2.2 and ERF Comparison
#
Slab
Depth
(mm)
Rebar
Depth
(mm)
Surface
Conc.
(%wt)
Init
Conc
(%wt)
D28
(m*m/s)
L365
Init
(yrs)
ERF
Init
(yrs)
Avg.
Diff
(%wt)
0 200.0 10.0 1.000 0.050 8.870E-12 0.1 0.1 0.02641412
1 200.0 20.0 1.000 0.050 8.870E-12 0.2 0.2 0.00321595
2 200.0 30.0 1.000 0.050 8.870E-12 0.5 0.5 0.00143871
3 200.0 40.0 1.000 0.050 8.870E-12 0.8 0.8 0.00137160
4 200.0 50.0 1.000 0.050 8.870E-12 1.2 1.2 0.00138123
5 200.0 60.0 1.000 0.050 8.870E-12 1.8 1.8 0.00139729
6 200.0 70.0 1.000 0.050 8.870E-12 2.3 2.3 0.00140854
7 200.0 80.0 1.000 0.050 8.870E-12 3.1 3.1 0.00148045
8 200.0 90.0 1.000 0.050 8.870E-12 3.8 3.8 0.00146977
9 200.0 100.0 1.000 0.050 8.870E-12 4.8 4.8 0.00150216
10 200.0 110.0 1.000 0.050 8.870E-12 5.8 5.8 0.00152166
11 200.0 120.0 1.000 0.050 8.870E-12 6.8 6.8 0.00154075
12 200.0 130.0 1.000 0.050 8.870E-12 8.0 8.0 0.001612981 The Crank Nicolson finite difference approach used in Life-365 v2.2 1-D slab and wall calculation is an
approximation to the Fick’s Second Law solution and thus an approximation to the error function direct
solution. To make the comparison, a particular set of Life-365 v2.2 parameters must be held constant,
including the surface concentration over time, the diffusion coefficient over time, and the external
temperature over time.
2 The values shown may not exactly match the current version of Life-365, due to continual refinements
being made to the codebase.
23
#
Slab
Depth
(mm)
Rebar
Depth
(mm)
Surface
Conc.
(%wt)
Init
Conc
(%wt)
D28
(m*m/s)
L365
Init
(yrs)
ERF
Init
(yrs)
Avg.
Diff
(%wt)
13 200.0 140.0 1.000 0.050 8.870E-12 9.3 9.2 0.00198084
14 200.0 150.0 1.000 0.050 8.870E-12 10.8 10.7 0.00325238
15 200.0 160.0 1.000 0.050 8.870E-12 12.7 12.1 0.00693507
16 200.0 170.0 1.000 0.050 8.870E-12 15.5 13.7 0.01761402
17 200.0 180.0 1.000 0.050 8.870E-12 22.2 15.3 0.05659158
18 200.0 190.0 1.000 0.050 8.870E-12 500.0 17.1 0.68549250

From left to right, the table lists the depth of slab, depth of reinforcing, constant surface
concentration, concentration to initiate corrosion, the constant diffusion coefficient, and
then the estimates of initiation period by the two techniques, and the average differences
in the values in the graphs exemplified by Figure 2.9. This figure specifically plots the 60
Life-365 point estimates of concentration (one for each ‘slice’ in the finite difference
mesh) against the ‘continuous’ error function estimates. Finally, it lists whether the ERF
value computed is valid, specifically, whether the error function computed a zero
concentration at the depth of the bottom of the slab. If it does not, then the error function
estimate is not directly comparable to the Life-365 estimate.
The table illustrates how for many of the comparisons done, the Life-365 v2.2 estimates
are nearly identical to the error function estimates. When the error function is not valid,
however, some of the estimates do not compare well at all. This is due to the fact that the
error function is not reporting a zero concentration at the bottom of the slab, when by
assumption and design the Life-365 finite difference approach specifically does.

Figure 2.9. Life-365™/ERF Comparison: Over Depth at Time of Initiation
2.2 Predicting the Propagation Period
The propagation period, tp, is fixed at 6 years. In other words, the time to repair, tr, is
simply given by tr = ti + 6 years. The only protection strategy that influences the duration
of the propagation period is the use of epoxy-coated steel, which increases the period to tp
= 20 years. The user can change the propagation period to reflect local expertise.
24
2.3 Repair Schedule
The time to the first repair, tr, is predicted by Life-365 from a consideration of the
properties of the concrete, the corrosion protection strategy, and the environmental
exposure. The user needs to estimate the cost and extent of this first repair (i.e., the
percentage of area to be repaired) and the fixed interval over which future repairs are
conducted.
2.4 Probabilistic Predictions of Initiation Period
Life-365 includes probabilistic predictions of the initiation period, based on Bentz
(2003). These predictions are calculated using the following steps:
a) Estimate time to first corrosion for the “best guess” or average values of the
inputs, that is, the values input by the user.
b) For each of five specific input variables (D28, Cs, m, Ct, xd), estimate five additional
time to first corrosions, where each is individually adjusted by 10 percent.
c) Use the results of steps b) and step a) to estimate the derivative of corrosion
initiation time with respect to each of the five variables. This determines the
sensitivity of initiation period to variations in each of the input variables.
d) Use the results from step c) to estimate a single parameter of variability, similar to
a standard deviation, for a log-normal assumed variation of time to corrosion
initiation (shown by Bentz to work well), where the average value of this
distribution is taken from the deterministic analysis in step a) and the variability
of this assumed distribution is determined from the results of steps b) and c).
2.5 Estimating Life-Cycle Cost
To estimate life-cycle cost, Life-365 follows the guidance and terminology in ASTM E-
917 Standard Practice for Estimating the Life-Cycle Cost of Building Systems. This
includes the process of
1. Defining a base year, study period, rates of inflation and discount, project
requirements, and alternatives that meet project requirements;
2. Calculating the present value of future costs;
3. Reporting results in present value (constant dollar) and current dollar terms; and
4. Conducting uncertainty and sensitivity analysis.
User Input Parameters
The user is responsible for providing the following cost information needed for the life-
cycle cost analysis:
• Cost of concrete mixtures (including corrosion inhibitors) for the various
corrosion protection strategies under consideration,
• Cost, coverage (percent of surface area), and timing of repairs,
• Inflation rate, i, and
• Real discount rate, r.
Life-365 provides the following default costs for the included rebars:
25
• Black steel = $1.00/kg ($0.45/lb)
• Epoxy-coated rebar = $1.33/kg ($0.60/lb)
• Stainless steel = $6.60/kg ($2.99/lb)
The user should review and if necessary change the costs of these materials to better
reflect actual project costs in his area.
2.6 Calculating Life-Cycle Cost and Current Costs
2.6.1 Life-Cycle Cost (Present Worth) Calculations
Life-cycle cost is calculated as the discounted present value of the initial construction
costs and the repair costs over the life of the structure (Figure 2.10). Life-cycle cost is
expressed in either total dollars or dollars per unit area of the structure (e.g. dollars per
square meter).

Figure 2.10. Construction and Repair Costs over the Life of the Structure
The initial construction costs are calculated as the sum of concrete costs, steel (or other
reinforcement) costs, and any surface protection (membrane or sealer) costs. The present
worth of all costs are specifically calculated as follows. First, Life-365 costs are inputted
in terms of what they cost today, specifically, what they cost in the first year of the study
period. To compute a cost’s discounted present value, then, it must first be inflated to the
future using an annual rate of inflation. (These inflated costs are the current costs listed I
the Life-365 life-cycle cost results.) Each future, inflated cost is then discounted to the
present value (first year) using the nominal discount rate (n), which represents the
combined effects of inflation and the real discount rate (d), the latter of which represents
the time value of money. The nominal discount is defined as the product of the annual
inflation rate (reflecting changes in the prices) and annual real discount rate (reflecting
the time value of money):
).1)(1()1( din ++=+ Eq. 16

Mathematically, given a cost 𝑐!! which occurs at time t but is expressed in terms of prices
at time 0, and inflation rate i, the current cost of that cost when it occurs is computed as
ti)1(c)(ccost current t0
t
0 += , Eq. 17

and the present value or constant cost of cost c in year t is calculated as
tt
t
dn
i
)1(
c
)1(
)1(c)(ccost constant luepresent va
t
0t
0
t
0
+
=
+
+
== . Eq. 18

26
3 Life-365™ Computer Program Users Manual
The concrete service life and life-cycle costing methodologies described in Chapter 2 are
implemented in the Life-365 Computer Program in a way that allows for easy input of
the project, structure, environmental, concrete, and economic parameters, and for rapid
sensitivity analysis of the parameters that most influence concrete servicelife and life-
cycle cost. This chapter describes how to install, start, and use the Life-365 Computer
Program, and then describes additional optional features designed for experienced
practitioners.
3.1 Installing Life-365
Life-365 runs on personal computers that can run Java, including those running Microsoft
Windows or Apple OS X. It requires Java 1.7 or higher (also known as “Java 7.0 or
higher”). Mac OS X now strongly prefers Java 1.7, which can be installed from the Java
website. Windows Java 1.6 and higher is produced by Oracle, and can be installed by
accessing http://java.sun.com and then selecting the appropriate web page for installing
the most recent version of the Java Runtime Environment [JRE].
To install Life-365 from either a CD or the Life-365 website (http://www.life-365.org):
• On Windows computers:
o Uninstall any previous versions of Life-365 v2.0 or higher that are
installed on the computer, by going to the Windows Control Panel,
accessing the “Add or Remove Programs” application, and removing these
versions of Life-365.
o Once removed, access the new version of Life-365 and then double-click
your mouse on the Windows install file; this will run through a quick
installation program that, among other things, puts a program-start icon in
your Programs folder.

• On Apple OS X computers:
o Double-click your mouse on the Apple install file; this will mount a disk
drive on your desktop. Open the disk drive and drag the Life-365 program
into your Applications Folder.
o Different versions of Life-365 can run simultaneously on Mac OS X,
although we recommend using only the most recent version.

3.1.1 If You Have Problems Installing on Windows Computers:
If the installation process exits abruptly without apparently installing any files, your
computer likely does not have Java installed or does not have at least Java 1.7 installed.
1. To see if Java is installed on your Windows computer, access the Control
Panel and then double-click on the Java icon (if you do not have a Java icon in the
Control Panel, then you very likely do not have Java installed). In the panel that
opens, select the “Java” tab and then the “Runtime settings...” or similar tab. On
this panel there should be a list of Java versions installed; check to see that Java
1.7 or higher is installed and enabled. Depending on the version of Windows, the
27
panel will look something like Figure 3.1; in this particular figure, there is only
version 1.7 installed; make sure other versions are not checked. Life-365 will
“ask” this particular computer’s Windows for a sufficient version and will “get”
the version it needs, 1.7.

Figure 3.1. Windows Java Settings Panel
You can also optionally verify that Java is installed by accessing the page
http://www.java.com/en/download/installed.jsp.
2. If you do not have Java installed or your installed version is less than Java 1.7
(6.0), you will need to install it. To install Java, search for “Java Runtime
Environment (JRE)” on the Internet (e.g., via Google) and go to the website that
offers the download of this JRE. Since Life-365 will run on Java 1.7, install the most
recent version of Java (which at the time of this manual’s release is Java 1.7). Then
download and follow its installation instructions. Once completed, return to the
Control Panel Java Settings Panel. Your computer should now display the version of
Java installed; make sure this version is 1.7 or higher.
3.1.2 If Problems Installing on Apple or Linux Computers:
1. To see if Java is installed on your Apple computer, start the Applications à
Utilities à Terminal program and at the command prompt, type “java -version”
(Figure 3.2). If Java is in fact installed, your computer will then return which version
of Java is installed; make sure this version is 1.7 or higher. If it is not installed, the
computer will return “command not found” or similar. If your computer runs a non-
Apple, Unix operating system, see that system’s users manual for information for
determining if and which version of Java is installed.
28

Figure 3.2. Determining Current Java Version in Mac OS X Terminal Console
2. If Java is not installed or you do not have at least Java 1.7 (7.0), you will need to
install it. To install Java, search for “Java Runtime Environment (JRE)” on the
Internet (e.g., via Google) and go to the Oracle website that offers the download of
this JRE for your operating system. Then download and follow its installation
instructions. Once completed, return to the Applications à Utilities à Terminal
program and at the command prompt type “java -version” again. Your computer
should now display the version of Java installed; make sure this version is 1.6 or
higher.
If you still have problems installing Life-365, please contact the Life-365 Consortium III,
at http://life-365.org/contact.html.
3.2 Starting Life-365
Installing Life-365 puts a start menu item labeled “Life-365” in your Windows Programs
folder (accessible from the Start button in the lower left-hand corner of your screen)
and an icon on your desktop; on Apple computers there should be a Life-365 icon in
your Applications folder. (Other, UNIX platforms may not, depending on your Java
settings). To start Life-365, simply select this menu item or the desktop icon.
When Life-365 starts for the first time, it will ask you to select the base units of measure
for your projects, either in SI metric, US units, or Centimeter metric. This selection
will determine whether all of your inputs need to be expressed in, for example, meters or
yards. If you decide later to change these base units, go to the Default Settings and
Parameters tab at the bottom of the screen, change the selection in the Base Units field,
and then press the Save button; all future projects will use this new base unit.
When Life-365 starts in general, your screen should look similar to Figure 3.3. This
screen has two components: on the left-hand side there is a navigation menu, under the
Navigator section, that lets you open new or existing Life-365 project files; under the
Settings section, it lets you change the default settings and get help with particular
screens; and under the Tips section, it displays text that gives you information and tips
on using the software.
29

Figure 3.3. Startup Screen
There are also three tabs at the bottom of the screen:
1. The Current Analysis tab, which contains the current project on which you
are working (on startup, this tab shows the opening banner in Figure 3.3);
2. The Default Settings and Parameters tab, which allows you to set the
default values of parameters to be used in all projects (see Section 3.9.1, p. 34);
and
3. The Online Help tab, which offers detailed explanations of the key windows
and features in the Life-365 Computer Program.
To start a new project, select Open new project from the left-hand-side navigation
menu; a complete project will be created for you, with two alternatives, each of
which has a baseline concrete mixture. To open a previously created and saved project,
select Open existing project…
When a new or existing project is opened, the main panel will show seven tabs at the
top. To conduct an analysis, each tab can and should be accessed from left-most tab,
Project, to right-most tab, LCC Report. Additionally, the left-hand Navigator pane has a
list of chronological Steps that divides your Life-365 analysis into logical analytical
components:
1. Define project: e.g., input the title, description, structure type, units of measure,
and economic values.
2. Define alternatives: e.g., input the titles and descriptions of the alternatives that
meet the project requirements.
30
3. Define exposure: input the location and type of structure (so as to set the
chloride and temperature exposure conditions).
4. Define mix designs: input the concrete mixture and corrosion protectionstrategy
for each alternative.
5. Compute service life: calculate the service life of each alternative.
6. Define project costs: input the initial construction, barrier, and repair costs and
repair schedule.
7. Compute life-cycle cost: calculate and sum the present value of all costs, for
each alternative, and compare.
Each of the software tabs that execute these steps is discussed in turn.
3.3 Project Tab
The Project tab allows you to complete Steps 1 and 2 above, specifically, to name the
project and set the type and dimensions of the structure, the economic analysis
parameters, and the number and names of the alternative projects (Figure 3.4).

Figure 3.4. Project Tab
Identify Project
In this section you can set the project Title, Description, Analyst, and Date, most of
which are used to simply document the project, but also are part of the report displayed in
and printed from the LCC Report tab (Figure 3.17).
Select Structure Type and Dimensions
In this section you set a number of fundamental parameters about the structure itself. Use
the Type of structure drop-down box to select the structure, which also sets the means of
chloride ingress, e.g., 1-D (one dimensional). Use the Thickness (for 1-D structures) or
31
Width (for 2-D structures), and Area or Total Length fields to set the total volume of
concrete, which is used to calculate total concrete installation costs, and to set the
surface area of the concrete structure, which is used to calculate repair costs. Use the
Reinf. depth field to set the distance over which chlorides travel from surface to the
steel reinforcement. Finally, use the Chloride concentration units drop-down box to
select the units of measure of the chloride exposure and concrete materials; if you select
SI metric or Centimeter metric as your Base unit, then your Concentration units
options are % wt. conc. and kg/cub. m.; if you select US units, then your options are %
wt. conc. and lb/cub yd.
Define Economic Parameters
Four parameters are used to set the period and interest rates over which life-cycle cost is
computed. Set the Base year to be the current year or other initial year that is relevant
to your analysis. Set the Analysis period to be the period of time over which life-
cycle cost should be calculated; 75 years is a common period and Life-365 allows the
user to select up to 200 years.
The Inflation rate (%) is the annual rate at which the prices of goods and services will
increase over the future; the Real discount rate (%) is the annual rate at which future
costs are discounted to base-year dollars, net of the rate of inflation (that is, it is the real
discount rate, which does not include the effects of changes in the prices of goods and
services). Federal infrastructure projects use a discount rate published in OMB
Circular No. A-94. Life-365 comes with the most recent figures of inflation and discount
rate, as suggested by the OMB Circular and as published in Energy Price Indices and
Discount Factors for Life-Cycle Cost Analysis (2006).3
At the time of this publication, the suggested long-run real discount rate was 2.0 percent
and the long-run general inflation was calculated to be 1.8 percent (based on the long-run
nominal discount rate of 3.8 percent and Eq. 16 (p. 25). Private sector projects, however,
can use their own rates of inflation and real discount.
Define Alternatives
Use this section to set the number, names, and descriptions of alternatives to be analyzed
and compared. Use the Add a new alt and Delete currently selected alt buttons to
create and delete alternatives, respectively, and double-click the mouse on the
alternative’s Name or Description fields to change them.
3.4 Exposure Tab
The Exposure tab (Figure 3.5) is used to set the exposure of the concrete to
external chlorides, and to set the monthly temperatures to which the concrete is exposed.

3 See: Rushing, Amy S., and Fuller, Sieglinde K., Energy Price Indices and Discount Factors for Life-Cycle
Cost Analysis, NISTIR 85-3273-18. Gaithersburg, MD: National Institute of Standards and Technology,
November 2012.
32

Figure 3.5. Exposure Tab
Select Location
When the Use defaults box is checked, you can select a Location, Sub-location, and
Exposure that closely matches the conditions of your project, and Life-365 will use its
database of locations to estimate the Max surface conc. of chlorides and Time to build
to max in the upper panel and the Temperature History in the lower panel. When the
Use defaults button is not checked, then the user must manually input these
concentration and temperature values. In Life-365 v2.2, the user can manually input their
own maximum chloride level by also using values measured in accordance with ASTM
C1556 (see Section 4 for details).
Define Chloride Exposure
The rate of buildup and maximum level of external chloride concentrations affect the
rate of chloride ingress and ultimately concrete service life. Use the following variables
to set these rates, and confirm them with the Surface Concentration graph on the right.
Max surface conc. – the maximum level of chloride buildup that the concrete
structure will experience over its lifetime, measured either in % wt. conc. or base
unit-specific units, i.e., either kg/cub. m. (SI metric) or lb/cub yd (US units).
Time to build to max (yrs) – the number of years for the buildup to reach its
maximum level. It is assumed that the buildup is zero at the beginning of the
structure’s life and that it increases linearly.
33
Define Temperature Cycle
When the Use defaults box is not checked, the user needs to input the annual temperature
cycle to which the project is exposed; these temperatures are part of the service life
calculations that determine the effects of temperature on concrete diffusivity. If the user
selected either SI metric or Centimeter metric as the Base unit in the Project tab, then
the temperatures must be input in degrees Celsius; if the user selected US units as the
base unit, then temperatures must be input in degrees Fahrenheit.
3.5 Concrete Mixtures Tab
The Concrete Mixtures tab (Figure 3.6) is used to define the concrete mixtures for
each project alternative defined in the Project tab.

Figure 3.6. Concrete Mixtures Tab
Define Concrete Mixtures
This section allows the user to input the concrete mixtures and corrosion protection
strategies of each alternative. Because the calculation of concrete service life is
computationally intensive, you need to press the Calculate service lives button after
inputting the mixtures and strategies to make the calculations.
Check-mark the Compute uncertainty box if you want Life-365 to compute
the uncertainty of service life for each concrete mixture. In general, this is a
calculation reserved for advanced users of Life-365; to understand Life-365
uncertainty analysis, press the Help button to the right, and see Section 3.10 (pg. 45) of
this manual for details on how to use service life uncertainty in your analysis. For
now, leave the Compute uncertainty unchecked.
34
Selected mixture
This section lists the properties of the concrete mixture selected in the upper, Define
Concrete Mixtures, panel, and allows you to edit these properties. To see the properties
of any one of your concrete mixtures, simply click the row of the mixture in this upper
panel.
Mixture group – use this section to set the water-cementitious materials ratio
(w/cm) of your concrete mixture, and whether and to what level you are using
SCMs (Slag, Class F fly ash, or Silica fume). Enter the SCM amounts in percent
substitution.
Rebar and Inhibitors groups – use these sections to select the type of reinforcing
steel used in your structure (Black steel, Epoxy coated, or 316 Stainless, which
affects the initiation period and propagation period of the concrete service life).
The Rebar% vol. concrete field is used to input the percent of the concrete that is
steel; this is used to calculate the cost of steel in your concrete structure, where the
costs of the steels are set in (1) the Individual Costs tab, under the Default
Concrete and Repair Costs tab), and (2) the Default Settings and Parameters
tab at the bottom of the Life-365 window. Use the Inhibitor drop-down to
include in your mixture any corrosion inhibitors that will be used. The units of
measure of these inhibitors are either l/cub. m. (liters per cubic meter) or gal/cub.
yd (gallons per cubic yard), depending on the Base unit selected in the Project tab.
Barriers group – use this section to include a membrane or sealant application on
the concrete. If the Use defaults box is checked, then you simply select
membrane or sealant; if not checked, then you must input the values of Initial
efficiency (%), Age at failure (yrs), and # times reapplied for the particular one
selected.
Custom Mixture Properties
In addition to inputting the constituent physical concrete mixture and other corrosion
protection strategies, Life-365 allows the user to input directly the model properties used
to calculate service life. (Doing so will potentially generate results that override one or
more of the basic Life-365 modeling assumptions, so check-marking the Custom button
the first time will cause a pop-up window to appear asking that the user confirm he is
aware of this.) The set of Custom input fields together override the model, in the
following ways.
Initial diffusion coefficient, D28. Inputting the initial diffusion coefficient directly
overrides the calculation of D28 based on w/cm ratio and the level of silica fume.
Diffusion decay index, m. Inputting this index directly overrides the calculation of
m based on the levels of slag and fly ash. The value of m, however must still be
between 0.2 and 0.6.
Hydration years. By default, Life-365 models hydration taking 25 years, where the
effects of hydration on concrete diffusivity are modeled by m; if under these default
settings the modeled concrete’s diffusivity continues to decline past 25 years, Life-
365 holds the concrete’s diffusion coefficient constant after 25 years. Inputting a
custom hydration value here changes the number of years after which hydration
35
stops; if you set the Hydration (yrs) field to 5, then hydration will stop after 5 years
and the diffusion coefficient will no longer decline (it may, however, still change
monthly due to the monthly changes in temperature).
Chloride concentration necessary to initiate corrosion, Ct. Inputting this value
overrides the initiation corrosions based on the type of reinforcing steel used (black
steel = 0.05 % wt. concrete, epoxy-coated = 0.05 %, and stainless steel = 0.5 %).
Propagation period. Inputting this value overrides the propagation periods based on
the type of reinforcing steel used (black = 6 years, epoxy-coated = 20 years, and
stainless steel = 6 years).
Service Life Graphs
The Service Life Graphs section contains a set of graphs that display the performance of
the concrete, by time and by the dimensions of the concrete structure.
Service Life. The Service Life tab (Figure 3.7) shows the service life of each
alternative concrete mixture alternative, in terms of the component initiation period
and propagation period.

Figure 3.7. Service Life Tab
Cross-section. The cross-section tab (Figure 3.8) shows a cross-section of the
chloride concentration of the concrete mixture at the point of initiation of
corrosion. The alternative shown is selected from the left-hand-side Select: drop-
down box.

Figure 3.8. Cross-section Tab
36
The chloride concentration scale on the left-hand side indicates the meaning of the
colors in the right hand graph. The top of the white rebar “holes” should have a
color that reflects the level of chloride concentration at initiation, which in this
graph is 0.05 % wt of concrete.
Initiation. This tab (Figure 3.9) shows two graphs: the concentration of chlorides
at the time of initiation, by depth of the structure (the left graph, Conc Versus
Depth); and the concentration of chlorides at the rebar depth, by point in time,
up to initiation (the right graph, Conc Versus Time at Depth). The left graph
includes a vertical dashed line indicating the depth of reinforcing, and the right
graph a dashed line indicating the year of initiation.

Figure 3.9. Concrete Initiation Graphs
The right graph shows that the Base case mixture hits initiation in 5 years at a rebar
chloride concentration of about 0.05 % weight of concrete, while the Alternative 1
mixture hits initiation in 17 years with a rebar concentration of 0.05 % weight of
concrete.
Concrete Characteristics. Finally, the Conc Characteristics tab (Figure 3.10)
displays two additional graphs that help interpret the performance of the concrete
mixtures. The left-hand-side graph, Diffusivity Versus Time, shows how the
calculated concrete chloride diffusivity changes over the initiation periods, by
mixture. The right-hand-side graph, Surface Concentration Versus Time,
shows how the concrete surface conditions change over the same period.

Figure 3.10. Concrete Characteristics Tab
37
For this particular graph, the left panel indicates that both mixtures have the same
chloride diffusivity characteristics (different mixtures could potentially have
very different characteristics and thus lines in this graph); the oscillations are
caused by the effect of annual temperature variation. The right-hand graph shows
that both mixtures have the same surface concentrations; this would not be true if
the mixtures had membrane or sealant applications.
3.6 Individual Costs Tab
The Individual Costs tab (Figure 3.11) allows you to edit the different constituent cost
and cost parameters, and view the effects they have on the constituent costs that make up
life-cycle cost.

Figure 3.11. Individual Costs Tab
Set Concrete Costs
In the upper-left corner of the screen, the Set Concrete Costs tab allows the user to set
specific values for the concrete mixture costs. Initially, this table displays the default
concrete cost that is listed in Concrete & Steel section of the Default Settings and
Parameters tab (located at the bottom of the Life-365 screen); this default cost
should represent the cost of concrete only, without inhibitors, barriers, or steel (these costs
are all used later, when calculating the initial construction cost). If, however, a particular
mixture uses, for example, SCMs or other materials that cause concrete costs to be
different than the default cost, enter that cost in this table, by double-clicking on the cost
itself; doing so will cause the User? box to be check-marked. If you enter a cost and need
to return that cost to the default cost, simply uncheck the User? box.
38
Default Concrete and Repair Costs
This section (Figure 3.12) lists the costs associated with three categories of project costs:
Concrete & Steel, Barriers & Inhib., and Repairs. When you first start your
project, Life-365 uses the default values of these costs listed in the Default
Settings and Parameters tab (located at the bottom of the Life-365 screen).
(These are converted, when necessary, from the units of measure listed in this tab to
the units used in your project. If you save your project and access it later, it will list again
your project values of cost.) If you would like to make the values currently shown in this
project to be the default values for all future projects, press the Set as defaults
button.

Figure 3.12. Default Concrete and Repair Costs
Costs for Each Alternative Mix Design
Based on these costs, the Project Costs section lists up to three costs: (1) the
Construction cost, or cost of mixing/placing the concrete; (2) the Barrier cost, or the
cost of applying a membrane or sealer; and (3) the Repair cost, orthe cost of
repairing the concrete over the study period. Use the Select Alternative drop-down
box to select which alternative you want to view in this panel, as well as in the Cost
Time-line for Alternative graph below.
Cost Timeline
This section shows a time-line of the project costs. The graph in Figure 3.11 shows in
particular the initial construction cost occurring between year 0 and year 1, and then
the repair costs starting after construction (as indicated by the red arrow) and
continuing every 10 years (as indicated by the vertical gray lines within the white
box) until year 75. Use the Select Alternative drop-down box above to see the
different cost timelines of your different alternative mixtures.
3.7 Life-Cycle Cost Tab
Once the project, exposure, concrete mixtures, and individual costs data have been
entered, the resulting life-cycle cost of the alternative mixtures are computed and can
be viewed and compared in the Life-cycle Cost tab (Figure 3.13).
39

Figure 3.13. Life-Cycle Cost Tab
Life-Cycle Cost
This first tab displays the life-cycle cost of each alternative, in tabular form, as a total
(the colored bars) and by component cost (the black and gray bars).
Timelines
The Timelines tab (Figure 3.14) shows the constituent costs over time. This tab will
initially show just one of the four timeline figures, but can show all four together when
the user checks the Show all four time series graphs together box. The upper two
panels show the individual-year and cumulative constant-dollar costs, that is, costs that
have been adjusted to account for the effects of increases in the prices of
materials and labor (the inflation rate) and time-value of money (the real discount
rate), and that are summed to compute life-cycle cost.
40

Figure 3.14. Life-Cycle Cost: Timelines Tab
The lower two panels show the individual-year and cumulative current-dollar costs,
which are the costs adjusted for inflation only. This current-dollar measure is not a
measure of life-cycle cost, but is a useful estimate of the actual dollars that are estimated
to be spent over the study period.
For these particular alternatives, the upper-right Cumulative Present Value gives a good
explanation of why Alternative 1 (the blue line in the graph) has lower life-cycle
cost: while it does have a slightly higher cost at initial construction and identical repair
costs, it has fewer repairs due to the longer service life (specifically, its first repair occurs
later), resulting in a total level in the last year of the study period that is lower than the
Base case (the red line).
Sensitivity analysis
An important component of life-cycle analysis is sensitivity analysis, or determining
how sensitive your results are to changes in any of the underlying assumptions or
inputs for economic, concrete, constituent-material, or repair costs. After making your
first, best-guess estimates of these parameters in the previous tabs, Life-365 gives you
at least two ways of conducting sensitivity analysis: the first way is to simply change
any of the parameters in the previous tabs and see what effects it has on each
alternative’s life-cycle cost. For example, you can easily change the environmental
conditions of the mixtures (e.g., switching location from New York, NY to Philadelphia,
PA) or some of the properties of your mixtures.
A second, efficient way to conduct sensitivity analysis on a subset of all parameters is
to use the Sensitivity Analysis tab (Figure 3.15). In this tab, you select one of the
predefined parameters listed in the left-hand tree (Discount rate (%) is selected in
the figure) and then select a range of values for this parameter by selecting from
41
the Variations drop-down box in the lower-left-hand portion of the tab (where, for
example, a 100 percent variation of an discount rate of 3 percent will create discount
rates of between 0 percent and 6 percent). Life-365 will then compute the life-cycle cost
of each alternative across this range of parameters and compare them in the right-
hand graph. The vertical dashed line is positioned at the value of the parameter you
selected as your “best guess” estimate.

Figure 3.15. Life-Cycle Cost: Sensitivity Analysis Tab
The graph in Figure 3.15 shows the effects of varying the discount rate between 0
percent and 6 percent (as indicated by the graph’s horizontal axis). The graph shows
that Alternative 1 has lower life-cycle cost than the Base case, regardless of the
(reasonable) real discount rate selected, that is, the life-cycle cost effectiveness of
Alternative 1 is insensitive to (reasonable) changes in the real discount rate. Sequentially
working through all of the parameters in the tree will allow the user to determine if the
results are sensitive to any of these input parameters.
42
3.8 Service Life and Life-Cycle Cost Reports Tabs
Finally, Life-365 provides two pre-defined reports of your project: an SL Report
(for “Service Life Report”; Figure 3.16) and an LCC Report (or “Life-Cycle Cost
Report”; Figure 3.17). These two reports list most but not all of the parameters used
in your analysis (your *.life file contains all of the parameters used). Each report can
be printed by pressing the printer icon in the upper-left corner of the window. If you want
to save the report as a PDF file, click on the disk-drive icon in the upper-left corner, select
“*.pdf” as the filetype, enter a file name, and save.

Figure 3.16. Service Life (SL) Report Tab
43

Figure 3.17. LCC Report Tab
Finally, you can copy and paste results from Life-365 to your own Word- and
PowerPoint-based reports, one of two ways. First, you can take “screenshots” of the
current window that are by default put in your clipboard for pasting. In Microsoft
Windows, a screenshot is taken by pressing the “Shift” and then “PrtSc” keys; on Apple
Computers, press “Shift,” “Apple,” and “3” simultaneously to take the screenshot. To
paste what is now in your clipboard to the Word or PowerPoint document, press
“Ctrl+v” in Windows or “Command+v” on Apple computers.
The second way to copy information from Life-365 is to hover the mouse over graphs
or tables, and right-click the mouse; a pop-up menu will appear (e.g., Figure 3.18) with
options to copy the information to the clipboard, or to export the raw data from the
figure or table.
44

Figure 3.18. Pop-up Menu for Copying a Graph to Clipboard
3.9 Supporting Features
In addition to the main, project-level windows, Life-365 includes a window for
setting default settings and parameters to be used in all of your analysis, and a window
offering context-sensitive help.
3.9.1 Default Settings and Parameters
The Default Settings and Parameters tab, shown in Figure 3.19, allows the user to
edit the parameters that are common across the different analyses, such as the units
of measure, location of project, economic conditions, and concrete costs.

Figure 3.19. Default Settings and Parameters Tab
45
Before conducting even your first analysis, it is recommended that you access this
tab and set the default settings to reflect your own conditions, particularly your
concrete, steel, and repair costs, and then press the Save button. Your first project,
then, will use your best estimates of these parameters.
3.9.2 Online Help
The Online Help tab (Figure 3.20) lists a series of pages describing the functionality of
and tips on using each window.

Figure 3.20. Online Help
Individual pages can be accessed by selecting from the drop-down box at the bottom
of the panel (in Figure 3.20, this box displays “Concrete Mixtures”). If, instead, you are
working on a particular window, say, the Project tab, and you want to access the
help page for that window, simply go to the left-hand navigation panel and select
Help for this window… from the Settings section; where available, a help window
will display with information for the

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